The heart has four chambers, the left and right atria and the left and right ventricles. The atria collect blood as it returns from the body in the case of the right atrium or from the lungs in the case of the left atrium. During diastole the atrioventricular valves (tricuspid valve on the right side and mitral on the left) open, filling the ventricles. During systole the ventricles contract closing the atrioventricular valves and expelling the blood towards either the body (left) or the lungs (right).
The bicuspid or mitral valve is located in the left atrioventricular opening of the heart. It is encircled by an annulus and consists of two valve leaflets of unequal size. The larger valve leaflet (called ventral or anterior cusp) is adjacent the aortic opening. The smaller leaflet is the dorsal or posterior cusp. The leaflets are composed of strong fibrous tissue which is thick in the central part but thin and translucent near the margin. The valves are constructed so as to pass blood unidirectionally from the left atrium to the left ventricle of the heart.
The tricuspid valve is located in the right atrioventricular opening and comprises three leaflets referred to as the anterior, posterior and septal cusps. The leaflets are roughly quadrangular in shape and attached to an annulus.
Both the mitral and tricuspid valves, also called a trio-ventricular valves, prevent regurgitation of blood from the ventricle into the atrium when the ventricle contracts. In order to withstand the substantial back pressure and prevent regurgitation of blood into the atrium during the ventricular contraction, the cusps are held in place by delicate chords which anchor the valve cusps to papillary muscles of the heart. These chords are of two types according to their insertion into the leaflet's free edge (“marginal chords”) or the body of the leaflet (“basal chords”). Among the basal chords there are two anterior and two posterior particularly thick and strong chords called “stay chords”.
In heart failure valve regurgitation often occurs due to dilatation of the valve annulus. When the leaflets fail to close completely during ventricular systole all the leaflet chords are under abnormal tension. The result of valve regurgitation is often associated with arrhythmias, chest pain, cardiac dyspnea, and other adverse clinical symptoms.
In heart failure, there is an apico-lateral displacement of the papillary muscles due to the increase in sphericity of the ventricles. This papillary muscle displacement pulls o the stay chords which in turn pulls the body of the leaflets towards the apex of the ventricle. This distortion of the valve geometry increases the mechanical stress of the myocardial fibers initiating a downward spiral of the ventricular contractility.
Therefore, a need exists for correction of distorted valve geometry by novel surgical techniques and devices.